Current Research

I currently coordinate a diverse collaborative group of scientists from the USDA Forest Service, The University of Vermont and other institutions that evaluate the influence of human-associated stress (e.g., pollution additions, climate change, etc.) on forest health and productivity.

This research concentrates on the impacts of anthropogenic stress on aspects of tree physiology, including tissue cold tolerance, carbohydrate and nutrient relations, foliar pigments and antioxidant enzymes.

Current issues that I am working on include: red spruce winter injury and other aspects of conifer cold tolerance, sugar maple decline, the impacts of calcium depletion on tree health, the biological basis of red pigment expression in the fall, and cold tolerance as a limitation to American chestnut restoration in the north.

Research Interests

I want to explore the possibility that human-induced change is not only subjecting forests to many new, complex, and potentially interacting stresses, but may be also eroding the natural biological and ecological mechanisms that forests rely on to respond, adapt to, and survive stress.

I will examine the cause and consequences of emerging tree decline scenarios (e.g., yellow cedar and birch decline) that have no apparent biologic (insect or disease) basis, but seem to be occurring with increasing frequency.

Why This Research is Important

Forests provide valuable ecosystem services (e.g., wood products, bioenergy, carbon sequestration, nutrient cycling, gas exchange, food and medical products, etc.) upon which all life and human societies rely. My research focuses on understanding and preventing the real-world decline of forest tree species - thereby preserving the continued flow of ecosystem services that are an important foundation for sustainable human health and prosperity.

National Research Highlights

What triggers fall red color expression in leaves? Forest Service scientists used a unique branch cooling system to verify that low temperatures cause sugars to build up in leaves and induce production of anthocyanin, a red pigment. Understanding the biology of anthocyanin production could help managers predict the timing, intensity, and location of fall color displays valued by the public.

Great news for disease-tolerant American elm! A grant from The Manton Foundation has provided the Forest Service’s Northern Research Station with an opportunity to accelerate American elm research in collaboration with Nature Conservancy.

A Forest Service scientist and his partners used a computer model to identify locations where inputs of acid deposition were expected to harm trees, and then tested those expectations using growth measures from red spruce trees at 35 stands in Vermont and New Hampshire. Model results indicated that trees in locations where acid deposition exceeded predicted tolerances had reduced growth over the last 60 years, suggesting that the model and associated maps could be valuable tools for locating vulnerable populations.